The invention generally relates to a system and technique for orienting and positioning a lateral string in a multi-lateral system.
A multi-lateral well includes a parent wellbore and one or more lateral wellbores that extend from the parent wellbore. Quite often, a main parent casing string lines the parent wellbore; and liner string(s) hang from the parent casing string and extend from the parent wellbore into the lateral wellbore(s).
Conventionally, for purposes of creating a multi-lateral well, the parent wellbore is first drilled and then cased with a casing string. A particular lateral wellbore may then be established by first milling a window (called a “parent casing window”) out of the wall of the parent casing string. The parent casing window forms the entry point of the lateral wellbore from the parent wellbore. After the lateral wellbore is drilled, a lateral liner string is run downhole so that the liner string hangs from the parent casing string and extends into the lateral wellbore. Depending on the particular multi-lateral system, the liner string may be cemented in place inside the parent casing string and/or may be sealed to the parent casing string.
It is often desirable to position the depth and orient the azimuth of the liner string with respect to the parent wellbore. For example, the liner string may have a window (called a “liner window”) that needs to be positioned at the correct depth and properly oriented for purposes of, for example, permitting fluid communication between the central passageway of the liner string and the central passageway of the parent casing string. Furthermore, the liner window when properly positioned and oriented may be used to provide mechanical access to the parent wellbore beneath the liner string window. This access may be used for purposes of an intervention into this part of the parent wellbore.
Conventional systems to orient the liner string include features that are located on the parent casing window. However, many such systems have typically been somewhat unreliable.
Thus, there is a continuing need for better ways to orient a lateral string with respect to a parent wellbore.